1. Field of the Invention
The present invention relates to a pivot head wrenching tool and, in particular, to a pivot head wrenching tool operable in a lock mode in which the pivot head wrenching tool includes a pivotal driving head restrained from being pivoted and in an unlock mode in which the pivot driving head can be operably pivoted.
2. Description of the Related Art
U.S. Pat. No. 7,509,893 shows a locking device for locking a pivotal head of a hand tool. A switch member includes a shank rotatably inserted in a recess defined in the pivotal head of the hand tool. The shank includes a convex and curved surface and a flat surface. A pawl and a spring are received in a passage. The pawl includes a plurality of teeth defined on a first end thereof. When the pawl is pushed to engage with the pivotal head, the teeth of the pawl engages with a plurality of engaging teeth defined on the pivotal head, and the convex and curved surface of the shank engages a second end of the pawl. Additionally, when the shank is rotated to a position such that the flat surface thereof contacts the second end of the pawl, the teeth of the pawl are disengaged from the engaging teeth of the pivotal head, thereby enabling the pivotal head to be operably pivoted. The problem that the hand tool suffers is that it requires a retaining means to prevent the spring from disengagement from the pawl. In addition, the elastic spring suffers a fatigue problem such that the spring can not push the pawl to an extent that enables the pivotal head to be retained in a desired position precisely.
The present invention is, therefore, intended to obviate or at least alleviate the problems encountered in the prior art.